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CAS: 1264756-25-3
MF: C25H9B2N2O2F2
MW: 428.96996
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Yi Xiao

Dalian University of Technology
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Jianzhang Zhao

University of Bath
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Co-reporter: Ling Huang;Xiaoneng Cui; Bruno Therrien; Jianzhang Zhao
pp: 17472-17482
Publication Date(Web):
DOI: 10.1002/chem.201302492

Abstract

C60–bodipy triads and tetrads based on the energy-funneling effect that show broadband absorption in the visible region have been prepared as novel triplet photosensitizers. The new photosensitizers contain two or three different light-harvesting antennae associated with different absorption wavelengths, resulting in a broad absorption band (450–650 nm). The panchromatic excitation energy harvested by the bodipy moieties is funneled into a spin converter (C60), thus ensuring intersystem crossing and population of the triplet state. Nanosecond time-resolved transient absorption and spin density analysis indicated that the T1 state is localized on either C60 or the antennae, depending on the T1 energy levels of the two entities. The antenna-localized T1 state shows a longer lifetime (τT=132.9 μs) than the C60-localized T1 state (ca. 27.4 μs). We found that the C60 triads and tetrads can be used as dual functional photocatalysts, that is, singlet oxygen (1O2) and superoxide radical anion (O2.) photosensitizers. In the photooxidation of naphthol to juglone, the 1O2 photosensitizing ability of the C60 triad is a factor of 8.9 greater than the conventional triplet photosensitizers tetraphenylporphyrin and methylene blue. The C60 dyads and triads were also used as photocatalysts for O2.-mediated aerobic oxidation of aromatic boronic acids to produce phenols. The reaction times were greatly reduced compared with when [Ru(bpy)3Cl2] was used as photocatalyst. Our study of triplet photosensitizers has shown that broadband absorption in the visible spectral region and long-lived triplet excited states can be useful for the design of new heavy-atom-free organic triplet photosensitizers and for the application of these triplet photosensitizers in photo-organocatalysis.

Co-reporter: Xiaoneng Cui, Azzam Charaf-Eddin, Junsi Wang, Boris Le Guennic, Jianzhang Zhao, and Denis Jacquemin
pp: 2038-2048
Publication Date(Web):February 11, 2014
DOI: 10.1021/jo402718e
A series of perylene derivatives are prepared as triplet energy acceptors for triplet–triplet annihilation (TTA) assisted upconversion. The aim is to optimize the energy levels of the T1 and S1 states of the triplet acceptors, so that the prerequisite for TTA (2ET1 > ES1) can be better satisfied, and eventually to increase the upconversion efficiency. Tuning of the energy levels of the excited states of the triplet acceptors is realized either by attaching aryl groups to perylene (via single or triple carbon–carbon bonds), or by assembling a perylene-BODIPY dyad, in which the components present complementary S1 and T1 state energy levels. The S1 state energy levels of the perylene derivatives are generally decreased compared to perylene. The anti-Stokes shift, TTA, and upconversion efficiencies of the new triplet acceptors are improved with respect to the perylene hallmark. For the perylene-BODIPY dyads, the fluorescence emission was substantially quenched in polar solvents. Moreover, we found that extension of the π-conjugation of BODIPY energy donor significantly reduces the energy level of the S1 state. Low S1 state energy level and high T1 state energy level are beneficial for triplet photosensitizers.

Yu Qin

Nanjing University
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Xiao-Bing Zhang

Hunan University
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Xiao-Bing Zhang

Hunan University
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